new pontoon cavitating

[bentley]

2010 20 ft bentley with a 50 hp 2 stroke mercury cavitates like mad cant run more than around 3000 rpm, motor is as low as it can go. what about spacing out transom

 

[Silvertip]

Re: new pontoon cavitating

1) Is the engine mounted full down on the engine pod?
2) Is this a long shaft (20-inch) motor.
3) Is this engine a Big Foot model?
4) What prop diameter and pitch is the current prop?
5) You are experiencing "ventilation" not "cavitation". There is a difference.

 

[lmuss53]

Re: new pontoon cavitating

I have a friend with a 2008 Bentley 20 footer with a Merc 50 ELPTO who ended up buying an extension kit to make the motor a XL 25inch. It cost around $500, and didn't effect his warranty since he let the dealer install it. I would have fooled with props a little before I tried that but he wanted to be done with it. It did eliminate all of the prop slip. I can get the details of where he bought the kit if you want to know.

The 2008 boat was bought on ebay after the company failed without any dealer involved. My friend was pretty much on his own with it. The Merc dealer was willing to sell him prop after prop but that was about all he had to offer.

I would ask your dealer to make your brand new boat work like it should.

 

[lakegeorge]

Re: new pontoon cavitating

Have dealer correct it.

 

[bentley]

Re: new pontoon cavitating

talked to the dealership today there service tech said it has to have the wrong prop on it so I went and got the number off of it and guess what its the correct prop, So I asked if it needs a motor with a longer shaft and he says no he sold several of these pontoon with the same set up and has not had any calls like this from the other customers, He wants me to bring it down to him and take it out on a nearby lake, He said the motor is the right length for the boat and cant beleive the transom is built incorrect

 

[lmuss53]

Re: new pontoon cavitating

Give him a chance to get it straightened out. Go along and make sure everyone agrees 100% if it is or isn't fixed. Good luck.

 

[rickdb1boat]

Re: new pontoon cavitating

The Bentley's transom, like many other manufacturers, sits high out of the water due to the large logs they have. The 50 HP motor is very light and will also sit higher in the water, as it doesn't have the weight to "push" down the transom deeper into the water. This is a common problem with newer toons when a small motor is installed. I have a 90 HP 4 stroke (400 lbs) on mine and it sits perfect in the water and has no ventilation. The solution I see would be to install a prop with extra cup and see if it helps or as was suggested, add an extension and make it a 25" shaft. I would personally add the extension and be done with it..

 

[FyreSarge]

Re: new pontoon cavitating

disregard. thanks

 

[bentley]

Re: new pontoon cavitating

talked to pontoon company today and they put me in touch with there service tech at there local dealership he told me the problem is in the prop that there is nothing wrong with using a 20 inch shaft motor on this pontoon, The prop he told me to use is 12 1/2 x 8 part # 48-42738A13 extra cupping Im going to try this prop thursday if it does not work its back to my dealership on friday
I hope this works, my dealership is 1 1/2 hours away I would like to save a trip. On top of it all my dealersips service tech seems to be at a loss. The prop on the boat now is a 12 x 10 1/2

 

[bentley]

Re: new pontoon cavitating

OK I installed the prop that the companys tech told me to and problem is gone, now to get the dealership to pay me back for the prop there tech still cant believe that prop worked best